I made a few devices in Eagle library. One is DS1307, the other 24AA256(EEPROM). I named the pins so that I have +5V and GND. After I dropped the components on to my schematic, I checked the PCB. Yes, the GNDs I named in the library are connected to the ground planes and the +5V pins are connected to power supplies.
On the other hand, the pins I named SCL in the two devices didn't connect on the PCB, neither did the SDA pins. I thought they would be connected since they're called the same name (shouldn't the netlist be doing this?).
So how do I make all SCL pins from different I2C devices I made in the library connect right after they're dropped on to the schematic? Thanks!
Pad names and signal names are not the same unless the pin is designated as a "power" pin in the library. So all the signals named "SCL" in the schematic will be connected, but all the IO pins names "SCL" in the library will NOT be connected.
This is really the way you want things; consider a package containing multiple identical gates (each one being a single symbol.)
Thank you for a quick response westfw. So I changed the property to pwr and called those pins SCL-1 and SDA-1. They connect automatically now. If in the future I make other I2C components and don't want them to connect automatically, I can just call those pins SCL and SDA.
If you don't actually want to draw connecting wires, normally you would draw a little net stub from the pin and name the net the same as the other nets you want connected. Any piece of net named the same will be ratsnested together on the PCB. Name a few nets SCL and they're all the same electrical signal.
I think westfw was saying that power nets are automatically connected just as an example of the only way this normally happens...I don't think he was suggesting you actually do it this way.
No, I don't think it's a good way to do things in general!
Hmm. So could you make an "SDA" part (symbol) similar to the GND/VCC symbols (defining a power net called SDA), that you could then drop down on all the appropriate chip pins that you wanted to bus together? As a sort of compromise ? I have to admit that drawing a large number of little stub networks (and naming them) is annoying...
I'm not sure if that's a compromise that you'd want to adopt, I think that ERC would complain about power being connected to a non-power pin. Plus the problem of sharing signals is too common to make a habit of creating a library part each time.
Renaming nets isn't that hard, especially if you use labels. I whipped up a little Eagle video example showing one approach:
Hmelyoff Labs VHCapture/VHScrCap, it used to be freeware but I'm not sure what's happening to it now, and it may only work on XP 32bit at the moment. There are other options out there like Camstudio which are just as good at capturing a whole window...I prefer VHScrCap for the mouse-follow behavior when it's needed.
